Eyepieces for a 6" Newt

Can anyone recommend a range of eyepieces that don't cost an arm and a
leg that are good enough for a 6" Newt at 100x plus magnification
(around 6mm in my case) ? How much should I be spending as a minimum ? I
picked a cheap eyepiece up from eBay for about 30 quid but I'm still not
sure if I am spoiling my experience for want of a few extra quid ...
Ditto for a decent Barlow - the one that came with my scope is junk.

Thanks !

regards,

Andrew